Smoothed Sprocket Overlay Prevents Bushing Damage

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Solution Overview

Problem

Machine components with overlays formed for improved wear resistance can become more damaging to other components due to low profile accuracy, leading to increased contact pressure and reduced lifespan of the other component.

Innovation Solution

A machine component with a smoothed overlay surface, featuring a matrix of second metal and hard particles dispersed within, arranged to prevent protrusion and exposure, and incorporating protrusions at the interface with the base to secure the overlay, achieved through forging to eliminate surface tension effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an overlay is formed on a machine component to improve wear resistance, then the durability of the machine component is improved, but the life of another component is reduced due to increased damaging effects

Engineering Contradiction:

Improvedurability of machine componentVSAvoiddamaging effects on other component

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by creating protrusions at the interface between the overlay and base (local region) to improve adhesion, while maintaining a smoothed surface in the contact region. This localized structural modification resolves the contradiction by preventing overlay detachment without compromising wear resistance, thereby reducing damaging effects on other components while preserving durability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs preliminary action by smoothing the overlay surface in the contact region before the component is put into service. This pre-smoothing process prevents future surface irregularities that would cause increased contact pressure and damaging effects, thus resolving the contradiction between maintaining durability and reducing harmful effects on other components.

Inventive Principle:

Principle #10Preliminary action

2Strength

If an overlay is formed by applying liquid material that solidifies, then wear resistance is improved, but profile accuracy is reduced due to surface tension effects, causing local increase in contact pressure

Engineering Contradiction:

Improvewear resistanceVSAvoidprofile accuracy of contact region

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The patent applies the taking out principle by removing (extracting) the surface tension effects and profile irregularities from the overlay surface through a smoothing process. This extraction of defects maintains the wear-resistant properties of the overlay while eliminating the manufacturing precision issues that would otherwise cause local contact pressure increases.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs parameter changes by modifying the surface parameters (roughness, profile) of the overlay in the contact region through smoothing. This changes the surface state from irregular to smooth, resolving the contradiction between maintaining the overlay's wear resistance and achieving sufficient profile accuracy to prevent excessive contact pressure.

Inventive Principle:

Principle #35Parameter changes

3Strength

If hard particles are dispersed in the overlay matrix, then wear resistance is improved, but hard particles may protrude from the surface and fall off during use

Engineering Contradiction:

Improvewear resistanceVSAvoidstability of hard particles on surface

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent applies beforehand cushioning by creating protrusions at the overlay-base interface that extend into the overlay material. These protrusions act as anchor points that prevent hard particles from protruding and falling off during use, thus resolving the contradiction between maintaining wear resistance and ensuring particle stability on the surface.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution effectively reduces damage to other components by minimizing contact pressure and preventing hard particle fallout, while maintaining excellent wear resistance.

Implementation Method 1

a material of the overlay in a liquid state is applied onto a machine component, which material then solidifies to form the overlay

Methodology Applied

Scientific EffectSolidification: Freezing

Implementation Method 2

The profile of the overlay is affected by surface tension in the liquid state and other factors

Methodology Applied

Scientific EffectSurface tension: Surface Tension

Implementation Method 3

This prevents a local increase in contact pressure and other phenomena, thereby making the machine component less damaging to another component

Methodology Applied

Scientific EffectPressure distribution: Pressure Gradient

Data Source

PatentUS10835982B2Machine component and method for producing the same

Publication Date: 2020.11.17 KOMATSU LTD

AI summary

A sprocket wheel, which is a machine component configured to slide relative to a bushing while being in contact with the bushing in an outer peripheral surface, includes a base made of a first metal, and an overlay that covers the base so as to constitute the outer peripheral surface. The surface of the overlay constituting the outer peripheral surface has been smoothed. Such a smoothed surface of the overlay makes the sprocket wheel less damaging to the bushing.